Chapter 12 - Leukocyte development, kinetics, and functions

types of granulocytes

neutrophils, eosinophils, basophils, mast cells

neutrophil - info

two forms, segmented and band, 50-75% of all WBC, innate immune system (not antigen specific, general immunity)

neutrophil - development

CMP-GMP-myeloblast-promyelocyte-myelocyte-metamyelocyte-band-neutrophil (segmented)

two pools of developing neutrophils in BM

proliferation (mitotic) pool - cells undergo mitosis

maturation (storage) pool - no longer divide but undergo maturation

myeloblasts

nucleus is round, 2-4 visible nucleoli (white spot), very large, the edge of the cell has dark edges

promyelocytes

nucleus is round to oval shaped (not centralized, very dark), full of primary azurophilic granules

myelocyte

last stage mitosis occurs, less granules, nucleus starting to condense to one side, cytoplasm more pink than blue, nucleoli are difficult to see

metamyelocyte

no longer divide, nucleus starts to look like a kidney bean (can’t draw a line through it), no nucleoli

neutrophil bands

highly clumped nucleus, c shaped nucleus, not clinically significant, 3 granules continue to form

neutrophil (PMN)

3-4 nucleus segments connected with threadlike filaments, more segments are called hypersegmented

neutrophil functions

primary function of phagocytosis and destruction of bacteria/fungi, generation of neutrophil extracellular traps (NETs, traps to kill bacteria/fungi)

eosinophil info

1-5% of WBC, either CMP/GMP-myelocyte-meta/band (don’t identify)-mature, have 2 segments, orange in color, cytoplasm has secondary granules, half-life is 18 hours (only show up when needed)

eosinophil functions

immune regulation, regulate mast cell function, production increased by parasitic worm, allergic response

basophil info

0.5-1.5% of WBC, rare so just separated by mature and immature, poorly understood b/c rare, life span much longer than other granulocytes; immature - round nuclei, blue cytoplasm, water soluble; mature - nucleus difficult to see from granules/very dark color, much smaller

basophil functions

poorly understood, player in allergic reaction, also involved in worm infections

mast cells

not leukocytes, tissue cells, similar phenotype to basophil and eosinophil, mast cell progenitor-tissue to mature, effector cell in allergic reactions, both anti-inflammatory and immunosuppressive functions

types of mononuclear cells

1 cell (not segmented), monocytes and lymphocytes

monocyte info

2-10% of WBC, GMP-monoblast-promonocyte-monocyte; promonocyte nucleus is round, 1 nucleolus present, blue cytoplasm; monocyte is large, cytoplasm is blue-gray, chromatin is loose pattern; no storage pool in BM, can divide faster if needed

macrophage info

once monocyte enters tissue its macrophage, lots of vacuoles and pale cytoplasm, either resident macrophage (Kupffer cells, survive much longer in tissue) or inflammatory macrophage (lifespan only hours, only response to inflammatory rxn)

macrophage functions

innate and adaptive immunity, removes debris from tissue damage/destruction of senescent red cells - “housekeeping”

types of lymphocytes

humoral immunity (adaptive, produce antibodies) - B cells

cellular immunity (attack foreign organisms) - T cells (adaptive) and NK (not adaptive)

lymphocyte percentages/origin

lymphocyte of WBC - 18-42%

B cell - 10-15%, develop initially in BM

T cell - 85%, develop in thymus

NK - 2%, develop in BM or thymus

lymphocyte functions

B cell - antibody production

T cell - mediate immune response and kill target cells

NK - kill tumor cells and virus infected cells

typical WBC counts in differential count

70 neutrophils, 20 lymoh, 10 monocytes